A major vaccination programme designed to slash methane production by sheep and cattle is underway in Australia.
Methane is a very potent greenhouse gas. Widespread vaccination could significantly reduce the animals鈥� contributions to global warming, say the vaccine鈥檚 developers at CSIRO, Australia鈥檚 national science agency. Vaccination could also boost the animals鈥� growth, they believe.
Farmers have so far signed up more than 635,000 sheep and 410,000 cattle for the programme. The vaccine works by targeting the bacteria that live in the animals鈥� stomach and produce methane.
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鈥淏ased on our current experimental results, we expect the commercial vaccine will be able to reduce methane emissions by about 20 per cent in these animals,鈥� says Rob Kelly of the CSIRO. Sheep and cattle produce about 14 per cent of Australia鈥檚 methane emissions, Kelly adds.
Jamie Newbold, who works on methods of reducing livestock methane production at the Rowett Research Institute in Aberdeen, UK, says: 鈥淭he researchers are being secretive about the vaccine, but the little bits of information that have been made public suggest that it looks very promising.鈥�
Four stomachs
Ruminants have a four-chambered stomach. In the forestomach, called the rumen, micro-organisms called methanogenic archae make methane as they break down food.
The vaccine triggers the animal鈥檚 immune system to produce antibodies to the bacteria.
If all cattle worldwide were vaccinated, global methane emissions would be cut by about five per cent, Newbold calculates. As a greenhouse gas, methane is 21 times more potent than carbon dioxide. 鈥淎 five per cent reduction would be considerable,鈥� he says.
Researchers did think that the bacteria might be important for normal digestion. But trials of the Australian vaccine suggest that this is not the case, says Newbold.
In fact, cutting methane production boosts the animal鈥檚 growth. Between two and 12 per cent of a cow or sheep鈥檚 energy intake is used for methane production by the bacteria. The CSIRO researchers found that the vaccine made more nutrients, such as hydrogen, available for use by the animal. This led to 鈥渕odest鈥� increases in productivity.
The CSIRO hopes to vaccinate one million cattle and two million sheep every year by about 2005. They are currently offering the vaccine for free. But its growth-boosting properties will probably persuade farmers to pay for it, says Newbold.
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